Paper trays for computer driven printer

Abstract: A computer printer tray system comprising a paper input tray (20) and a paper output tray (70), neither of which is required to have any moving parts. The output tray (70) is supported in part by the input tray (20) and both trays of the system are semi-permanently cantilever supported from the front of the printer so that neither tray has to be removed when loading an unprinted stack of cut sheet paper or removing printed paper. The output tray (70) has a first portion (74) which is inclined from a second portion (76) by about 10° to correct paper curl caused by a wet printing process.

Description: The present invention relates to paper input and output trays for computer driven printers, and, more particularly, for inkjet printers. Inkjet printers have been provided with permanently attached paper input trays which necessarily give the printer a larger footprint during shipping thus requiring larger containers than are required for printers having detachable paper input trays. Printer paper input and output trays are regularly accessed by the printer operator and may be removable or permanently attached trays. The former are removed from the printer whenever the paper supply is exhausted for refilling with a stack of cut sheet paper. Printers with removable trays, e.g. as shown in EP-A-0 498 561, occupy a smaller footprint and therefore can be shipped in smaller containers but they have other drawbacks. Removable trays usually have a spring biased pusher plate beneath the paper stack for urging paper upwardly toward the printer feed rollers which remove one sheet at a time from the stack. Repeated removal, loading and reinstallation of the paper tray in the printer is a relatively easy task provided that care is taken to properly remove the tray, load the paper and reinstall the tray. Despite ordinary precautions, through repeated usage, removable paper trays, and the parts thereon such as the pusher plate and particularly the parts thereof that connect the tray to the printer, are subject to wear and eventual breakage. Similarly, paper output trays are ordinarily easily removable trays which are hung on the front of the printer with plastic hooks or the like which are subject to breakage. Particularly in printers such as inkjet printers which apply print to the paper using wet ink, paper curl which usually takes place about the long center axis of the paper is also a problem. Accordingly, a semi-permanently attached paper tray system for a printer such as an inkjet printer is desired which, after installation by the user, is intended to remain in place on the printer even during paper loading so as to minimize the frequency of tray removal and attendant breakage. Both trays of the system should still be removable when desired without special tools and both trays should be easily accessible, preferably from the front of the printer, whereby paper can be loaded into the input tray without removal of either the paper input tray or the paper output tray. The paper input tray preferably should have no moving parts. The present invention provides a paper input tray for a computer printer as defined in claim 1. The details of an exemplary embodiment of the invention will be clear from the following description in conjunction with the accompanying drawings, in which: Figure 1 is an exploded perspective view of a computer driven printer showing the printer chassis with the paper input and paper output trays removed. Figure 2 is a top plan view of the paper input tray. Figure 3 is a front elevation view of the paper input tray. Figure 4 is right side elevation view of the paper input tray. Figure 5 is a left side elevation view of the paper input tray. Figure 6 is a bottom plan view of the paper input tray. Figure 7 is a vertical cross section taken at line 7-7 on Figure 2. Figure 8 is a vertical cross section taken at line 8-8 on Figure 2. Figure 9 is a perspective view of a spring biased paper shelf which is pivotally mounted to the printer chassis proximate the paper input tray. Figure 10 is a perspective view of the left side chassis plate of the printer. Figure 11 is a perspective view of the right side chassis plate of the printer. Figure 12 is a top plan view of the paper output tray. Figure 13 is a front elevation view of the paper output tray. Figure 14 is right side elevation view of the paper output tray. Figure 15 is a left side elevation view of the paper output tray. Figure 16 is a bottom plan view of the paper output tray. Figure 17 is a vertical cross section taken at line 17-17 on Figure 12. Figure 18 is a vertical cross section taken at line 18-18 on Figure 12. The exploded view of Figure 1 shows a printer 10, particularly a desk top printer such as an ink jet printer which has a paper input tray 20 and a paper output tray 70 located thereabove. Ordinarily, the paper input tray 20 is first inserted into the printer and is retained therein and suspended from the printer chassis in cantilever fashion on the front of the printer. The paper output tray 70 is installed immediately above the paper input tray and is partially supported thereby. When inserted in the printer, the trays are attached in such a fashion that they are, while removable, not intended to be regularly removed from the printer and in fact the input tray need not be removed from the printer for loading of a fresh supply of paper unlike various prior art paper cassettes or trays which must be removed whenever they are to be reloaded. Accordingly, the paper tray system of the present invention is referred to as a semi-permanently attached paper tray system. The paper input tray 20 will be described first. The input tray is molded plastic and has a horizontally extending shelf 22 and a pair of integrally molded upstanding sidewalls 24, 26. A paper size adjustment shelf 28 is slidably attached to the front side 30 of the paper input tray and has a front endwall 29 which is adjustably positionable to accommodate different sizes of paper in the tray as is well known. Each of the sidewalls 24, 26 is in the form of an inverted channel having a rearwardly extending tray support arm 25, 27 which is received in the printer to support the -paper input tray 20 in cantilever fashion from the front of the printer chassis. The left side inverted channel tray support arm 25 has an upper horizontally extending web 28 which comprises an output tray support surface. Vertically extending from the upper web 28 is an exterior flange 30 and an interior flange 32. The interior flange portion of the arm 25 extends rearwardly and has an outwardly extending hook 34 at it's free end. The hook has a beveled portion 36 to facilitate insertion of the arm into the printer left hand chassis plate 50 (Fig. 9) and a forwardly facing stop shoulder 38 which engages a rearwardly facing stop shoulder 58 in a pocket 60 in the left hand printer chassis plate 50 to resist removal of the input tray from the printer. The left arm interior flange 32 is laterally resilient so that the hook 34 will move laterally inwardly against the bias of the resilient arm 25 as the beveled surface 36 of the hook 34 engages the left printer chassis plate 50 during insertion of the paper input tray into the printer. The right hand arm 27 is also in the form of an inverted channel having a horizontally extending web 40 which comprises an output tray support surface and a pair of vertically extending interior and exterior flanges 42, 44. The interior flange 42 of the right arm also includes a hook 47 and the flange 42 of the right arm 27 is also preferably laterally resilient so that the right hand hook 46 can engage a complementary receiving pocket 62 in the right hand printer chassis plate 60 (Fig. 10). Each of the interior flanges 32, 42 on the left and right arms has a shaped male end 33, 43 to facilitate insertion of the arms into complementary shaped female receiving apertures 53, 63 in the printer chassis plates 50, 60. Upwardly facing notches 37, 47 (Figs. 7 and 8) in the horizontally extending web support surfaces 28, 40 are provided to receive downwardly facing projections on the paper output tray 70 (to be described in more detail below) for properly positioning it above the paper input tray. As seen in Figure 6, the bottom of the paper shelf 22 is preferably molded with a plurality of criss-cross stiffening webs 23 and a pair of downwardly extending resilient rearwardly facing hooks 48, 49 (also seen in Figures 7 and 8) which engage printer chassis structure to resist upward movement of the front edge of the paper tray after it has been fully inserted into the printer. Figure 9 schematically shows a pivotally mounted spring biased paper shelf 130 having a pair of ears 132 at the front corners thereof which are received on opposed horizontally extending half axles 134 which extend from the left and right chassis plates 50, 60 of the printer (Figs. 1, 10 and 11). The lower end of compression spring 136 seats against the printer chassis and pushes the underside of the rear portion of the shelf 130 upwardly. When a stack of paper is loaded onto the paper input tray, the front portion of the paper rests on the shelf 130 so that the leading edges of the paper sheets are biased upwardly toward paper pick rollers, not seen. Figures 10 and 11 respectively comprise perspective views of the left and right chassis plates 50, 60 of the printer which preferably comprise molded plastic vertically extending plates each having a front endwall 54, 64 and a generally horizontally extending interior female shelf 56, 66 which receives the male arms 25, 27 of the paper input tray 20. The beveled camming surfaces on the hooks 34, 36 on the interior ends of the arms are received in horizontally extending recesses 57, 67 in the side chassis plates until the hooks engage a beveled surfaces 58, 68 at the ends of the recesses 57, 67 which urges the resilient arms 25, 27 inwardly toward each other so that the hooks can enter retaining pockets 60, 62 in the chassis plates 50, 60. The lower edges of the flanges 30, 32; 42, 44 of the arms 25, 27 are thus supported on upwardly facing surfaces 59, 69 of the female recesses 57, 67 and the endwalls 54, 64 of the chassis side plates substantially engage vertically extending edges 55, 65 of the vertically extending exterior and interior flanges 30, 32; 42, 44 of the paper input tray arms. The paper output tray 70 comprises a molded plastic shelf 72 having a front horizontal portion 74 and a rear portion 76 which is downwardly inclined from the front portion at an angle of about 10°. The downwardly inclined rear portion 76 includes a pair of upwardly extending sidewalls 78, 80 and a rear endwall 82 which is received in the printer. The rear inclined portion 76 of the shelf has a pair of downwardly extending flanges 84, 86 at the lateral edges thereof and a pair of guide ears 88, 90 at the lateral edges of the rear inclined portion. Each ear has a rearwardly open general horizontally extending elongated slot 92, 94 therein which engages a retaining pin which extends inwardly from each of the side chassis plates 50, 60 in the printer. The bottom plan view of Figure 16 shows that the ear 88 and one lateral edge 96 of the inclined portion (the right edge as seen in Figure 16) is inwardly offset from the marginal flange 86 of the front portion of the tray and has an inclined camming surface 98 which assists in centering the tray in the printer during installation thereof by engaging a correspondingly beveled surface on the left hand printer chassis sideplate 60. The output tray 70 also has a rearwardly and forwardly extending guide wing 100 depending downwardly from the undersurface of the rear portion 76 proximate the left side edge thereof. The wing 100 has a rearwardly and upwardly extending guide surface 102 and a forwardly and upwardly extending guide surface 104 which respectively engage the left hand printer chassis plate 50 to lift the left hand tray edge during attachment to and removal of the tray 70 from the printer. When properly positioned, the paper output tray wing 100 is received in a pocket in the left hand printer chassis plate such that the front portion of the tray is properly oriented horizontally. Figures 17 and 18 show vertically extending webs 106, 108 integrally molded on the underside of the output tray whose lower edges 107, 109 define horizontally extending output tray support surfaces which engage the horizontally extending web support surfaces 28, 40 on the printer input tray arms 25, 27. Downwardly facing projections 110, 112 on the output tray support surfaces are received in the previously described upwardly facing notches 37, 47 on the paper input tray web support surfaces. A plurality of vertically extending stiffening webs 114 is also shown on the underside of the horizontal and inclined surfaces of the paper output tray which also has a sliding shelf 120 to accommodate paper of different lengths. The tray system thus far described, but not the spring biased paper shelf 130, is disassembled from the printer during shipment and, upon installation in the printer, the paper input tray 20 is first inserted with the hooks 34, 46 snapping into place in their respective pockets 60, 62 in the printer chassis and with the lower hooks 48, 49 engaging printer structure to resist upward movement of the front edge of the paper input tray. The laterally resilient arms 25, 27 of the paper input tray firmly resist removal of the tray from the printer under ordinary conditions but are sufficiently resilient to allow them to be manually bent toward each other for tray removal when desired. The paper output tray 70 is next inserted into the printer such that the ears 88, 90 and slots 92, 94 engage the pins in the printer at which time the downwardly extending projections 110, 112 are aligned with the notches 37, 47 in the paper input tray so that the paper output tray is supported in the printer and on the paper output tray. Inclination of the rear portion 76 of the paper output tray at an angle of about 10° with respect to the horizontal portion 74 of the output tray reduces paper curl along the longitudinal axis of the paper which typically occurs in wet process printers such as ink jet printers. This paper curl about the long axis is automatically straightened in the present output tray because the printed paper. bends about the line of intersection between the horizontal portion of the tray and the inclined portion of the tray as it is deposited thereon. The present tray system occupies a small footprint in the shipping container and is also user friendly since the user need not remove the tray from the printer when loading paper therein nor manually straighten curl in the printed paper.

Claims: A paper input tray (20) for a printer comprising: a generally horizontal paper shelf (22), a pair of upstanding sidewalls (24, 26) and a front endwall (29) having a portion extending upwardly from said shelf (22), each of said sidewalls (24, 26) having a cantilevered tray support arm (25, 27) extending rearwardly therefrom, said arms each having an upper edge (28, 40) for supporting a paper output tray (70) and a hook (34, 46) at a free end thereof, each hook being receivable in a pocket (60, 62) in said printer (10), characterised in that at least one of said arms (25, 27) is resilient so that it latches semi-permanently in its pocket (60, 62) to retain the input tray (20) in position on said printer. A computer printer paper tray system comprising: a paper input tray (20); a paper output tray (70); and means (28, 40) for supporting said output tray on said input tray cantilevered from a printer (10); said input tray being as defined in claim 1. The tray system of claim 2, wherein said at least one hook includes a bevelled camming surface (36) which causes said hook to move horizontally against the bias of said resilient arm as said hooks are inserted into said pockets, said hooks also having a forwardly facing stop shoulder (38) engageable with a rearwardly facing stop shoulder (58) in said pocket to resist removal of said input tray from said printer. The paper tray system of claim 2 or 3, wherein said tray support surfaces on said arms extend in generally horizontal planes. The paper tray system of claim 4, wherein said arms comprise inverted channels each having spaced vertically extending interior and exterior flanges (30, 32; 42, 44) and a horizontal web (28, 40). The paper tray system of claim 5, wherein said interior flanges (32, 42) are each resilient in a horizontal direction and have a shaped male end (33, 43) which facilitates insertion of said arms into complimentary shaped female receiving apertures in said printer, said hooks (34, 46) being on said male ends. The paper tray system of claim 6, wherein said arms each have an abutment thereon which prevents insertion of said arms into said apertures beyond predetermined limits. The paper tray system of claim 7, wherein said resilient arm (27) is longer than the other arm (25) to provide greater horizontal movement of said hook thereon. The paper tray system of claim 8, further comprising interengaging means (37, 47; 110, 112) on said input tray and said output tray to position said output tray on said input tray. The paper tray system of claim 9, wherein said interengaging means comprise upwardly facing notches (37, 47) on said support surfaces (28, 40) and downwardly facing projections (110, 112) on the paper output tray (70). The paper tray system of claim 10, further comprising a downwardly extending resilient rearwardly facing hook (48, 49) on said shelf for engaging printer structure to resist upward movement of the front edge of said paper input tray (20). The paper tray system of any of claims 2 to 11, wherein said output tray (70) comprises a shelf having a front horizontal portion (74) and a rear portion (76) downwardly inclined from said front portion, a pair of side walls (78, 80) and a rear end wall (82) each upwardly extending from said rear portion; a pair of downwardly extending guide ears (88, 90) at the lateral edges of said rear portion, each ear having a rearwardly open generally horizontally extending elongated slot (92, 94) therein; said tray having a rearwardly and forwardly extending guide wing (100) depending downwardly from the undersurface of said rear portion proximate one side edge thereof, said wing having a rearwardly and upwardly extending guide surface (102) and a forwardly and upwardly extending guide surface (104) respectively for engaging printer structure (50) for lifting said one tray edge during attachment to and removal of the tray from the printer; and a horizontally extending output tray support surface (107, 109) on the underside of said inclined portion beneath said side walls thereof. The paper tray system of claim 12, further comprising a vertically extending stop surface thereon on each of said sidewalls to prevent insertion of said output tray into said printer beyond a predetermined limit. The paper tray system of claim 13, wherein said output tray guide wing (100) is located laterally inwardly of the sidewall closest thereto and laterally outwardly of the ear on said sidewall. The paper tray system of claim 12, wherein said rear portion (76) is inclined about 10° from said front portion (74). A computer printer (10) comprising: a chassis (50, 60); a paper input tray (20); a paper output tray (70); and means for semi-permanently supporting said output tray on said input tray cantilevered from said chassis; said input tray being as defined in claim 1.

Inventors: CLEVELAND LANCE, FIRL GEROLD, ZANTOW TIMOTHY, CLEVELAND, LANCE, FIRL, GEROLD, ZANTOW, TIMOTHY
Applicants: HEWLETT PACKARD CO, HEWLETT-PACKARD COMPANY
Application year: 1994
Main classification: B41J11
IPC codes: B65H1, B65H31, B41J13